1. Field of the Invention
The invention pertains to apparatus and a method for centrifugally casting a babbitting material to a cylindrical bearing shell.
2. Description of the Prior Art
It is known in the commercial prior art to provide a centrifugal casting or babbitting machine in which the cylindrical bearing shell is mounted between opposite end plates on a structure similar to a lathe bed with a fixed headstock having a rotatable plate, and a movable, clamping tailstock plate. The prior art commercial device also includes what may be called a runner trough into which molten babbitt is ladled and from which the molten babbitt passes into the interior of the bearing shell through a conduit extending through the idling end plate. The arrangement known to me as being commercially available also includes a gas heater arrangement for applying heat to the runner trough to prevent the molten babbitt from solidifying in the runner trough. The particular commercial machine of which I am aware also includes an arrangement for spraying cooling water into the space around the bearing shell after the molten babbitt has been applied to the trough and bearing shell.
In another commercially used arrangement of which I am aware a gas-fired heated babbitt tank is located in spaced-apart relation from the idler end plate of the machine and a removable pipe connects the lower end of the tank with the interior of the babbitt shell. A valve on the tank is manually opened for a predetermined time to meter the quantity of babbitt desired for the particular bearing. This arrangement, used for relatively large bearing shells, includes an arrangement for lowering the molten babbitt tank to facilitate loading the tank with the solid babbitt material to be melted, the tank then being elevated to an operating position.
Neither of these arrangements are considered to be wholly satisfactory in my estimation for a number of reasons. First, the manual operations of handling torches for maintaining certain parts at adequate temperatures and the manual ladling of molten metal, introduces problems of safety. The operation of ladling or in any other way of feeding babbitt in other than a continuous pour can frequently result in an inferior bond of the babbitt to the bearing and the presence of porous and laminated layers of babbitting. I attribute such undersirable results as stemming from the intermittent pouring as well as the inexact control of process temperatures, spinning speeds, cooling and pouring times. Another disadvantage of commercially used casting apparatus is that due to the lack of precise pouring controls, excess babbitt is often poured into the casting. As a result of the excess babbitt, increased costs are encountered in the additional machining required as well as the recycling cost for the excess babbitt.
For these and other reasons it is my view that the production level under the prior art arrangements is relatively low compared to what is available from an arrangement in accordance with my invention, and that the rate of rejection with an arrangement according to the invention is substantially reduced.
Accordingly, the aim of my invention is to provide an apparatus and method for centrifugally casting babbitt in which the disadvantages of the prior art commercial arrangements are substantially avoided.